pluck.js
725 Bytes
import { map } from './map';
export function pluck(...properties) {
const length = properties.length;
if (length === 0) {
throw new Error('list of properties cannot be empty.');
}
return (source) => map(plucker(properties, length))(source);
}
function plucker(props, length) {
const mapper = (x) => {
let currentProp = x;
for (let i = 0; i < length; i++) {
const p = currentProp != null ? currentProp[props[i]] : undefined;
if (p !== void 0) {
currentProp = p;
}
else {
return undefined;
}
}
return currentProp;
};
return mapper;
}
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